Answer: triggerfish

AnswerCrossword Clue
TRIGGERFISHPuffer's relative
triggerfisha kind of fish, with a large spine on the forsal fin which can be locked upright by a second smaller spine
triggerfishA marine fish occurring chiefly in tropical inshore waters. It has a large, stout dorsal spine that can be erected and locked into place, allowing the fish to wedge itself into crevices